The present invention relates generally to cement compositions and their use and more particularly, to cement compositions useful in self-leveling coating formulations useful for producing floors.
In the construction industry, buildings typically have floors made of concrete. Concrete floors are manufactured from an aqueous mixture of Portland cement and aggregate, e.g., sand, that is applied to a suitable substrate and finished to provide a smooth surface. The aqueous cement-based mixture cures and hardens, forming a concrete floor. The cured concrete floor must be substantially straight and level prior to applying finished flooring such as tile or carpeting.
The aqueous mixtures, containing cement, sand and water, are viscous liquid mixtures that are typically not self-leveling so that laborers must use troweling tools to smooth the surfaces of the mixtures once they have been poured or otherwise applied to the substrate. Troweling tools create rippled surfaces which require additional manual labor for smoothing. The cured concrete floor is typically uneven, although this may not be noticeable to the untrained eye.
In an effort to reduce the cost of labor and the difficulty of leveling poured cement, cementitious materials have been developed having self-leveling characteristics. These coatings are typically applied over an uneven floor substrate as a thin coating which must be applied in a sufficiently thick layer to fill the depressions in the surface of the uneven floor substrate so that the final, level surface is composed solely of the applied coating.
Various compositions useful for providing a poured self-leveling flooring surface have been described in the prior art; see, e.g., U.S. Pat. No. 4,159,912 of Jorgenson, U.S. Pat. No. 4,394,175 of Cheriton et al., U.S. Pat. No. 5,378,279 of Conroy, U.S. Pat. No. 5,403,394 of Burgand and U.S. Pat. No. 5,424,099 of Stewart et al.
There still exists a need for an economical self-leveling coating composition that provides high-quality, very smooth-surfaced cement-based flooring with high compressive strength, excellent durability and freedom from cracking and shrinkage. The present invention provides a cement composition that may be economically shipped long distances from the manufacturing site and formulated at the job site into a free-flowing self-leveling, self-smoothing coating that can be used to prepare high quality cement-based, self-leveling floors.